By Sid Perkins
Radar altimeters on Earth-orbiting probes can detect and count small icebergs even under cloudy skies, providing warning to ships and invaluable data for scientists monitoring climate change.
Large icebergs that cast off from Antarctica on a regular basis, some the size of small European countries, are slow-moving and therefore easy to track (SN: 5/12/01, p. 298). Their smaller kin, however — including kilometer-sized chunks that break off the larger behemoths as they melt — threaten ships just as much as the large bergs, says Jean Tournadre, an oceanographer at the French Research Institute for Exploitation of the Sea in Plouzané. Those smaller bits of ice, besides being harder to spot from space, are often masked by consistently cloudy conditions, he notes.